For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Tim Maas
I came across an excellent exposition on this topic simply by Googling the questioner's inquiry, with the response viewable at:
https://www.google.com/search?q=how+do+we+develop+the+fruit+of+the+Spirit%3F&rlz=1C1RXMK_enUS1076US1076&oq=how+do+we+develop+the+fruit+of+the+Spirit%3F&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIJCAEQABgeGKkGMggIAhAAGBYYHjIICAMQABgWGB4yCAgEEAAYFhgeMggIBRAAGBYYHjIICAYQABgWGB4yCAgHEAAYFhgeMggICBAAGBYYHjIICAkQABgWGB7SAQkyMDg5NGowajeoAgCwAgA&sourceid=chrome&ie=UTF-8